Check on Diodes of Dual Power Supply Circuitry
1.Equipment Needed
28V DC ground power source.
2.The First Test
(1)Preparations.
·Disconnect the following circuit breakers on 4α panel:A4,A8,B1,B9,B14,B13,B16,B11,B12,A10 and A15.
·Disconnect the following circuit breakers on 5α panel:F1,F2,F3,F4,F5,F6,F7,F8,F9,and F10.
·Disconnect circuit breaker M2 on 2α panel.
·Start engines on the ground.
(2)Check and Trouble-shooting Measures.
·As Nr increases,check the warning sounds from the horn when Nr reaches the maximum and minimum values.If the sounds come back abnormal,change diode 28E on 2α panel or circuit breaker L3.
·Put inverter switches 38X and 39X at“ON”position and check if the 250VA AC power system outputs power and if indicators“INV.1”and“INV.2”go out.If not,check diode 46X and circuit breaker D8 on 4α panel.
·Disengage switch 8F on 12α panel and check the temperature of the pitot tube.Then engage switch 8F to see if the temperature rises.If not,check diode D6 on the 3α panel and circuit breaker D6 on 4α panel.
·Check the display on the fuel gauge 1Q.If there is no display or if the display is not correct,change the fuel gauge.
·Engage fuel transfer switch on 3Q panel and check if the fuel is transferred normally based on the reading on the fuel gauge.If not,check diode D4 on 2α panel and circuit breaker L6.
·Press the test button on 7α panel and check if the landing gear warning indicator“L.GEAR”3G lights up.If not,check diode 56G on 2α panel and circuit breaker L9.
·Put switch 8E at“FIRE”position and check if fire warning indicator 2E(“FIRE”)lights up.If not,check diode D3 on the 3α panel and circuit breaker L4 on 2α panel.
·Check if the CSAS works normally.If not,check circuit breaker D10 on 4α panel.
·Check if the emergency horizon works normally.If not,check circuit breaker G2 on 5α panel.
·Check if the super-emergency power system works normally.If not,check circuit breaker G3 on 5α panel.
·Check if the engine parameter acquisition and display system works normally.If not,check circuit breaker C5 on 4α panel.
·Check if HNS(Hybrid Navigation System)works normally.If not,check circuit breaker H6 on 5α panel.
·Press test button 2D.Check if indicators“CARGO.F”and“O/HEAT”on 7α panel light up.If not,check diode 3W on 32Δ connection box and circuit breaker C9 on 4α panel.
·Check if windshield wipers work normally.If not,check diode D1 on 3α panel and circuit breaker C16 on 4α panel.
·When power is supplied to the helicopter,check if the master warning indicator“ALARM”and most of the indicators on 7α panel light up.If not,check circuit breaker L8 on 2α panel.
·When power is supplied to the helicopter,engage the illumination switch on 12α panel and check if there is illumination in the instrument panel,instruments on the central console,circuit breaker panel,dome control panel and so on.If not,check circuit breaker D15 on 4α panel.
·When power is supplied to the helicopter,indicator“HYD.LEVEL”on 7α panel lights up.If not,check diode D28 and circuit breaker C11 on 4α panel.
·Disconnect the emergency illumination battery.Put the emergency illumination switch and cockpit illumination switch at“ON”position and check if the dome light lights up.If not,check circuit breaker C15 on 4α panel and diodes D1,D2,D3 and D4 on 126L support.
·Shut down engines on the ground and use GPU as the power source.
·Press test button 20G next to the GPU power socket and check if indicator 24G lights up.If not,unplug GPU and engage circuit breaker F8 on 5α panel.Then plug in GPU and press test button 20G.If indicator 24G lights up,replace diode D11 of 19G or 13P on 1α panel.If 24G still doesn’t light up,unplug GPU,disconnect circuit breaker F8 and engage circuit breaker F9 on 5α panel.Then plug in GPU and press 20G.If 24G lights up,change diode D9 on 2α panel or circuit breaker G9 on 5α panel.
(3)Finishing Touches.
·Engage all the circuit breakers that have been disengaged.
·Put all the switches that have been operated in 2.2 back to their previous positions.
·Unplug GPU.
3.The Second Test
(1)Preparations.
·Disengage circuit breaker 13P in main power distribution box 1α.
·Disengage circuit breakers L1,L2,L3,L4,L6,L7,L8 and L9 on circuit breaker panel 2α.
·Disengage circuit breakers C9,C16,C14,D3,D4,D6,D8,D15,C11,C15,C5,and D10 on circuit breaker panel 4α.
·Disengage circuit breakers G9,G3,H6,and G2 on circuit breaker panel 5α.
·Start engines on the ground.
·Check if the CSAS works normally.If not,check circuit breaker A10 on 4α panel.
·Check if the emergency horizon works normally.If not,check circuit breaker A4 on 4α panel.
·Check if the super-emergency power system works normally.If not,check circuit breaker F6 on 5α panel.
·Check if the engine parameter acquisition and display system works normally.If not,check circuit breaker M2 on 2α panel.
·Check if HNS works normally.If not,check circuit breaker E9 on 5α panel.
(2)Check and Trouble-shooting Measures.
·As Nr increases,check the sounds from the horn when Nr reaches the maximum and minimum values.If the sounds come back abnormal,check diode 27E and circuit breaker B13 on 4α panel.
·Put switches 38X and 39X at“ON”position.Check the output voltage of 2×1000VA AC power system on the EPD and check if indicators“INV.1”and“INV.2”go out.If not,check circuit breaker A8 and diode 47X on 4α panel.
·Disengage switch 8F on 12α panel and check the temperature of the pitot tube.Then engage switch 8F and the temperature of the pitot tube shall increase.If not,check diode D9 on 3α panel and circuit breaker B1 on 4α panel.
·Check the display of the fuel gauge.If there is no display or if the display is not correct,replace the fuel gauge.
·Engage the fuel transfer switch on 3Q panel and check if the fuel is transferred normally.If not,check diode D1 on 2α panel and circuit breaker F3 on 5α panel.
·Press the test button on 7α panel and check if the landing gear warning indicator(“L.GEAR”)lights up.If not,check circuit breaker F10 and diode 57G on 5α panel.
·Put switch 8E at“FIRE”position and check if warning indicator 2E(“FIRE”)lights up.If not,check diode D2 on 2α panel and circuit breaker F5 on 5α panel.
·Put switch 9E at“FIRE”position and check if warning indicator 1E(“FIRE”)lights up.If not,check diode D2 on 3α panel and circuit breaker F7 on 5α panel.
·Press the test button 2D and check if indicators“CARGO.F”and“O/HEAT”light up.If not,check diode 2W on 32Δb connection box and circuit breaker B9 on 4α panel.
·Check if windshield wipers work normally.If not,check diode D4 on 3α panel and circuit breaker B16 on 4α panel.
·Check if navigation lights light up normally.If not,check diode D7 on 4Δ connection box on 3α panel and circuit breaker B14 on 4α panel.
·When power is supplied to the helicopter,check if the master warning indicator“ALARM”and most of the indicators on 7α panel light up.If not,check circuit breaker B12 on 4α panel.
·When power is supplied to the helicopter,engage the illumination switch on 12α panel and check if there is illumination in the instrument panel,instruments on the central console,circuit breaker panel and dome control panel light up.If not,check circuit breaker A15 on 4α panel.
·When power is supplied to the helicopter,check if indicator“HYD.LEVEL”on 7α panel lights up.If not,check diode 29D and circuit breaker B11 on 4α panel.
·Connect the emergency battery for illumination.Put switches for emergency illumination and cockpit illumination at“ON”position and check if the dome light lights up.If not,check if the emergency battery for illumination works normally.
·Shut down engines on the ground.
·Press the test button 20G next to GPU power socket and check if indicator 24G lights up.If not,unplug GPU and engage circuit breaker G9 on 5α panel to draw power from the battery.Then plug in GPU and press 20G.If 24G lights up,replace diode D6 on 2α panel or circuit breaker F9 on 5α panel.If 24G still doesn’t light up,unplug GPU,disengage circuit breaker G9 on 5α panel and connect the main power distribution box 13P to draw power from the battery.Then plug in the GPU and press 20G.If 24G lights up,change diode D10 in device 19G or circuit breaker F8 on 5α panel.
(3)Finishing Touches.
·Unplug GPU.
·Engage all the circuit breakers that have been disengaged.
·Put all the switches that have been operated back to their previous positions.